National leader John Key says the Government is too busy knocking him to focus on important issues.

At the weekend's Labour Party conference Mr Key was the butt of jokes, satirical songs and criticism of him was a big part of Deputy Prime Minister Michael Cullen's closing speech.

This morning Mr Key told reporters Labour was spending too much time attacking him and not concentrating on the economy and rises in food and power prices.

Dr Cullen said the Government has been rolling out policy "at a great pace" but some issues were international, like food prices.

"The Government can't legislate international food prices and international oil prices down."

Dr Cullen said National has spent the past 8½ years criticising the Government.

Dr Cullen said Mr Key needed to toughen up.

"This is election year. This is a year where both parties actually get to attack each other, it's not a one-sided contest of poor little John sits in his corner and nobody criticises him and he just sort of smiles beatifically all the way through to the election.

"This is a contest about power in New Zealand and who can be the best government for New Zealanders and he's going to have to get used to the fact he's playing with the big boys now."

He told reporters to expect action in the House today over asset sales.

During the weekend congress Dr Cullen accused Mr Key of throwing aside his principles to say what he thought the public wanted to hear.

He called Mr Key "slippery" and criticised him over not stating his views on the Springbok tour, voting against civil unions when he previously said he did not have a problem with them, supporting the Iraq war, and a range of other issues.

Prime Minister Helen Clark today said she did not think the attacks were over the top and in the main Labour had been focusing on rolling out its policies.

She said it was difficult to attack an "empty brand" - a reference to Mr Key's lack of policy.

"By and large one does ignore an empty space. We've got a lot to talk about ourselves with big policies rolling out, big ideas in housing, big ideas in education, big ideas in trade...things that will make a difference on the ground for Kiwis."

On asset sales, Miss Clark said she believed National would try to use infrastructure bonds to dilute the shareholding of state owned enterprises (SOEs).

"What I think he's been working on with merchant banks is equity instruments whereby they would severely dilute the ownership of state-owned enterprises," she told reporters.

"So they would say hand on heart, `no no we're not selling we just happen to have totally diluted the ownership'," she said.

"Frankly swamping the shares of ownership in a SOE is exactly privatising it. So I think some hard questions need to be asked."

The Government has also issued infrastructure bonds, most recently to help fund major roading projects, but Miss Clark said that did not qualify as privatisation.

During the weekend Miss Clark described asset sales as "a defining issue".

Mr Key said he disagreed: "the defining issue of the election will be the economy".

He said it spoke volumes that Labour used its election year congress to focus on him.

"They didn't spend any time on the economy they spent their time on two issues: one, working out ways to rort the Electoral Finance Act and secondly, indulging themselves in low grade personal attacks on me."

Mr Key said he did not intend to be distracted on main issues like interest rates and workers leaving for Australia.

He disagreed with Dr Cullen's list of 15 areas he claimed Mr Key had backtracked on.

"He should be focusing on the economy that's facing some quite serious issues instead he is spending his time reading every transcript that I give trying to look for the odd umm that's in the wrong place."

A Labour blogger has posted a video on video sharing website YouTube of Mr Key saying he could not remember his position on the 1981 Springbok rugby tour of New Zealand.

That tour tore New Zealand society down the middle, as South Africa still had an apartheid regime at the time.

"It doesn't personally bother me, they can spend their whole time in the election campaign if they want having a go at me."